s t i L o u v r e s

NAP SILENTFLO T H E E X P E R T S I N N O I S E C O N T R O L .

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Flowline - .

design of commercial and industrial plant rooms ariably requires the passage of large volumes of air;

a t is usedfor cooling, for consumption by engines or ressors and for ventilation o r a i r conditioning.

ny installations, this airflow is created by noise

rating equipment and the designer or engineer is faced the problem of allowing the a i r to get in, and at the

e time, preventing the noise from getting out of the

room: This criterion is often quite important,

larly when a low pressure drop is required and

ant acoustic performance is necessary to minimise annoyance. When one also considers that the

ztect will generally require an attractive, practical

ution a t low cost, then it is simple to understand

the mul ti-purpose NAP Flowline Acoustic Louvres

L o u v r e s

D e s c r i p t i o n NAP Flowline Acoustic Louvres are designed for easy

installation and for applications where space is limited, and to provide a superior acoustic performance and low regenerated noise levels under a wide range of operating conditions.

Aesthetically pleasing, they consist offabricated metal louvre blades with acoustic infill, alternated with a i r gaps

andfitted into afour-sided metal case. The open area of the louvre has been carefully optimised for maximum a i r flow

and acoustic performance and the entry to each airway is streamlined for low resistance.

The ai r flow and pressure drop characteristics, excellent

acoustic performance and balanced proportions of NAP

Flowline Acoustic Louvres makes them popular with

architects and engineers.

Long life and freedom from maintenance are assured by the use of galvanised steel, Aluminium or stainless steel sheet

and inert non-combustible acoustic infill.

The acoustic and airflow performance of these louvres are

guaranteed and supported by independent test results.

A o o l i c a t i rn Because of their excellent noise reduction capability,

NAP Acoustic Louvres can be used in almost any situation

which must permit the flow of air, but control noise.

The modular design and wide range of sizes and finishes allows them to be used in most industrial or

commercial projects.

Typical applications include: W Plant room ventilation

Cooling towers

F r e s h air intake

Compressor houses Power stations

W Electrical transformer houses

W Ventilation exhaust plenum chambers

W Diesel generator sets

W Car Parks

W Air conditioning plants W Refrigeration plants

W Process air intakes Naturally ventilated areas

M o d e l s

Sixes Practical sizes should be chosen, given due consideration to

manufacture, handling and transport. Large areas can be

formed by a combination of modules and necessary structural frame. (Dimensions shown are typical, but may

vary depending on overall louvre height).

H - l i n e M o d e l

NAP Acoustic Louvres are available in two models, S-line

(Slimline) and H-line (High Performance Louvre), and

each model is available in depths o f300mm or 600mm.

300 S-line The specially designed, low profile blades, are set at a pitch

of 15Omm and at an angle which prevents line-of-sight

through the louvre, resulting in an enhanced high frequency

acoustic performance and an extremely low pressure drop.

600 S-line This model is comprised of a '300 S-line' as the front or exposed unit and another 300mm long unit (similar in

construction to the '300 S-line') and when joined back to

back, forms a chevron blade profile.

300 H-line The specially designed, substantial blades are set at a

pitch o f300mm and provide a superior low frequency

acoustic performance in the critical 63Hp, 125Hz and 250Hz octave bands.

600 H-line This model is comprised of a '300 H-line' as the front or

exposed unit and another 300mm long unit (similar in

construction to the '300 H-line') and when joined togetheu,

provide an even greater low frequency acoustic performance for extreme applications.

S - l i n e M o d e l

Weight The weight of Acoustic Louvres is given in the table below.

For difierent sizes, alter the weights proportionately.

To obtain weights of 600 S-line and 600 H-line models,

multiply weight of the appropriate 300 model x 1.85.

300 S-line Acoustic Louvre Weights (kg)

Nominal Width (mm) Nominal Height (mm) 500 1000 1500 2000 900 29 53 76 100

Acoustic Louvre Weights (kg) Nominal Width (mm)

Nominal Height (mm) 500 1000 1500 2000 900 32 60 88 115 1200 43 79 115 152 1500 53 98 143 188 1800 63 117 171 225 2100 66 136 199 261 2400 84 155 226 298

Standard Construction The case sides are fabricated from galvanised sheet steel.

The specially designed Acoustic Louvre blades of the 300

models are sheathed with galvanised sheet steel on the top

(outward) face for weather protection and incorporates a

raised lip which prevents the ingress of water; the bottom

(inward) face is sheathed with perforated galvanised sheet steel for maximum sound absorption.

The rear unit of the 600 S-line and 600 H-line models, which is not exposed to the weather, gives extra sound absorption by sheathing both sides of the louvre blades with perforated galvanised sheet steel.

In most instances were 600 H-line or 600 S-line are specified the louvres are generally supplied in a single case.

However, for di_fficult installations they can be supplied in two halves. This must be detailed at the time of ordering. A c o u s t i c P e r f o r m a n c e The acoustic infill of the louvre blades is inert and non-combustible and is retained so that particle fatigue or The acoustic performance of NAP Flowline Acoustic

corrosion does not occur. Louvres has been measured in accordance with the American Standard ASTM E336-67T, Section A2.3

Where exposed to severe weather or in wash down 'Test Procedure for Measuring Transmission Loss in

A bird guard, manufactured from 25mm square galvanised Australian Test Laboratory.

wire, can be suppliedfitted to the rearface of all models, This test procedure enables the determination of the ij required. Noise Reduction which is the difference in sound pressure

Alternative Construction levels between a reverberant enclosure and the freefield.

fie Acoustic Louvres can be supplied in Aluminium or The Jield Transmission Loss is determined from the same

steel for superior co,-,.osion resistance and overall appearance. standard and is equivalent to the Noise Reduction less 6dB.

Generally the perforated blade bottom remains galvanised Noise Reduction due to cost and lead time, however; aluminium or stainless This term is widely used with many interpretations, but is steel pegorated blade bottoms are available upon request. generally accepted as being the dqference in levels between

Finish a reverberant enclosure and the free field, when separated

NAP Acoustic Louvres are usually supplied unpainted, but by the test section.

if requested they can be supplied powder coated in a choice ~~i~~ ~ ~ d ~ ~ t i ~ ~ ( d ~ ) of standard colours. Octave Band Centre Frequency ( H z )

Special projects often require special finishes and the NAP 63 125 250 500 l k 2k 4k 8k

Aluminium Acoustic Louvres can be supplied in plain, 300s-l ine 7 9 11 16 19 23 24 21

powder coated or anodised finishes. 600 S-line 7 11 14 23 33 43 44 40 300 H-line 9 13 15 17 20 19 21 21

Flowline aerodynamic performance data

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L o u r v e F a c e V e l o c i t y ( m l s e c )

The NAP Flowline Acoustic Louvre requiredfor a

particular application can be determined by following this simple procedure:-

1. Establish the acoustic criterion required for a given location, external to the room containing the noise source (for NR vaiues, refer to AS 1469-1973 'Criteria curves

for Rating Noise and Establishing Acoustic Environment').

Typical NR Values Sound Pressure Levels (dB)

Note that the approximate relationship between the dB (A) level of a noise and the NR number is dB(A) =NR+3.

2. Estimate the distance from this point to the face of the Acoustic Louvre. Calculate the distance attenuation from the diagram below.

Attenuation with respect to noise level just outside Louvre

D l s t a n c e f r o m f a c e o f L o u v r e ( m )

3. Establish the Sound Pressure Level inside the room, by acoustic measurement or prediction techniques.

4. Subtract rhsults in step 2 from results in step 4 and establish the required Noise Reduction. Select the Acoustic Louvre which has a Noise Reduction greater than thesefigures,

particularly at low frequencies. If no Acoustic Louvre matches the required performance, consult your NAP agent

5. I f the acoustic criterion can be met by using a S-line or a H-line Acoustic Louvre, the next step is to calculate the pressure loss. Having selected the appropriate model,

determine the airflow requirements. 6. The Acoustic Louvre size can be established by one

of two methods.

(a) by deciding the maximum pressure loss, readfrom the pertinent airflow graph and determine the muximum face velocity; the louvre face area is the total airflow divided bj this maximum face velocity, OR

(b) select a louvre size and calculate theface velocity. If the losses are too high, increase the louvre face area and recalculate.

7. The correct louvre is a cbmpromise between the optimum of the three conflicting requirements, ie. size, pressure drop and acoustic performance. Remember that these are ACOUSTIC louvres and this aspect should havefirst priority,

otherwise, a great deal of effort and expense is wasted. 8. When the calculations suggest a certain size mid-way

between models, always select one size larger rather than

one size smallel:

Typical Airflow and Pressure Loss Calculation;-

1. Airflow requirement: 85001itrelsec=8.5m3/sec.

Maximum allowable pressure drop=Pa. 2. From Face Velocity graphs, relating to the 600 S-line

Acoustic Louvre, the maximum face velocity is 2.6mlsec. 3. The louvreface area is then 8.5/2.6m=3.3m2. 4. The louvre selected must fit the Architect's physical

requirements. An A'coustic Louvre, nominally 1800mrn high would be: 3.3/1.8=1.83m wide.

For the lowest cost and ease of ordering, select a louvre 1850mm wide.

Typical Selection Procedure Octave Band Centre Frequency ( H z )

125 250 500 lk 2k 4k 1. Criterion: NRSO at 10m 66 59 54 50 47 45 2 .1W louvre distance 13 13 13 13 13 13

attenuation 3. Acceptable Lp at 1 metre 79 72 67 63 60 ' 58 4. Lp in plant room

(measured or predicted) 87 83 80 83 74 70 5. NR required

(Line 4 - Line 3) 8 11 13 20 16 13 This can be achieved by both the 600 S-line or the 600 H-line models. In this case, choose the 600 S-line model.

6. Noise reduction of 600 S-line 11 14 23 33 43 44

7. Is our Criterion met? Yes

Acoustic Louvres shall be NAP Flowline Acoustic Louvres,

S-line or H-line models. They shall be fabricated from

galvanised sheet steel, Aluminium or stainless steel sheet.

The acoustic blades shall be filled with inert,

non-combustible acoustic material. Where required, a corrosion resistant wire bird guard shall be provided.

The Acoustic Louvres shall have a certified airflow and

acoustic performance provided by an independent

NATA registered Australian Testing Laboratory (and must

meet the acoustic performance shown on page 4) .

I n s t a l l a t i o n

The most common application of NAP Flowline Acoustic

Louvres is in plant room plena or in compressor and power

houses. Where duct work connection are required, it is

preferable to use NAP D-Series Duct Attenuators.

In most applications, the Acoustic Louvre is installed after

construction of walls, we recommend that a clearance gap of 1Omm be left on each of the three sides.

To ensure the best acoustic performance and for the most

attractive finish, it is recommended that the Acoustic Louvre

be mounted flush with the external wall by one of the methods

shown andfixed with appropriate anchors (drill holes on

site to suit). Any gaps between case and wall at fixing points

must be packed to avoid distortion to the louvre case. After fixing, seal all gaps with a non-setting compound.

flange width is 75mm untess specifled otherwise

masonry anchors I

fixlng flange, fix to Louvre on site flange width is 75mm unless specified otherwise

I Louvre

E x t e r n a l F l x l n g I n t e r n a l F l x l n g

,masonry anchors

,weatherproof seal

S l d e F l x l n g

Multiple Louvre Applications In applications of single module in height and multiple

modules in width, Acoustic louvres are bolted together

through the case sides in pre-drilled holes. A thin bead of

non-setting compound is applied to the sides, front and

back, to ensure that noise will not penetrate through minute gaps between the louvre cases. '

In applications of single module in width and multiple

modules in height, Acoustic Louvres can sit on top of one

another, with a se2f-adhesive compressible PVC gasket

between each unit, front and back.

In applications of multiple modules in width and height,

which will involve a structural frame, it is recommended that your NAP agent be consulted.

NAP SILENTFLO T H E E X P E R T S I N N O I S E C O N T R O L

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p e y C G r e a t N o r t h R o a d r D o c k , N .S .W. 2 0 4 6 m e : ( 0 2 ) 9 7 1 2 0 7 2 2 i ( 0 2 ) 9 7 1 2 0 8 2 2